Cold Engine Idle Issue

[sgretchko]

For the first 10 minutes or so when the car is started on a cold morning, I have an idle issue. When stopping after driving for a few miles, the idle drops down to between 2 and 3k. The car rumbles slightly and feels as if it might stall, then seems to correct itself. Once the car is warmed up throughly, it doesn't seem to happen. Also, check engine light came on for a few minutes, but went out before I could have it checked. Any thoughts or ideas? Thank you in advance.

[landar]

For the first 10 minutes or so when the car is started on a cold morning, I have an idle issue. When stopping after driving for a few miles, the idle drops down to between 2 and 3k. The car rumbles slightly and feels as if it might stall, then seems to correct itself. Once the car is warmed up throughly, it doesn't seem to happen. Also, check engine light came on for a few minutes, but went out before I could have it checked. Any thoughts or ideas? Thank you in advance.

I am guessing that you mean 200-300 RPM idle rather than 2-3k RPM? The latter range would be very high.

Couple of thoughts. Try to get an OBDII scanner on the port. There may still be some info you can glean. Also, do some research on the IACV (Idle Air Control Valve). It may be in need of cleaning. Some owners clean the throttle body as it may have restrictive plate movement due to carbon buildup.

Also, could be a sensor (perhaps an engine temp sensor) is on the fritz.

Here is a thread on the IACV. You can do some searching for additional info -> http://us.lexusownersclub.com/forums/index.php?showtopic=67203&st=0&p=422963&hl=iacv&fromsearch=1entry422963

[sgretchko]

Sorry, 200 to 300 rpm's. Thank you for your advice.

[cardona6569]

Hello: If you have an older LS this is normal but It can be improved. You first need to clean the Throttle Body with a good T-Body cleaner. Check your air filter. Clean your airflow sensor. You should pay special attention to the front of the TB there are some small things on the upper part near where you took off the air intake hose, those get flooded with gunk. That should help your car to get up to 400 rpm and that where is going to be for the most part unless air temp needs it to be in any other higher setting or you are using the AC. If the car stalls you have a hosing problem, with some of the vacuum lines, many of them are brittle by now. Check and replace, but one at a time, because you can get them switch and have stalling problems. You could also change your idle speed control but that is a 600.00 plus part that might get your car all the time at 600 +-50 RPM's. But do you want to spend the money? No I would not. And Ultimately after all that, you could also change or repair your computer, another ton of money. Best practical solution clean up and use it at 400 rpm's which it would not be a great problem and will ultimately save you gas. Note before doing anything with the Idle speed control or computer need to have this diagnosed by a competent shop/dealer or tech not on your own, unless you are one of the above because we are talking mega bucks. Just trying to help with a pragmatic approach. CCF